My experience with generic Harvoni was that I had some headaches during the first 3 weeks and I also do recall having slept a little bit more than I usually do. After the 3 weeks of tx I felt well, with energy, no foggy brain, etc.
My advice would be to use the time and rest enough if you feel you need it, especially if you do not have other side effects to bother you. Also doing some exercises (walking, easy jogging) helps. Also drinking water helps too.
It is great that you started the tx, I wish you an easy trip till EOT and afterwards towards SVR12